Made available in DSpace on 2014-10-09T12:54:55Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:07:32Z (GMT). No. of bitstreams: 1 12799.pdf: 2207492 bytes, checksum: b4b02c1b606e22ff23dfa5bb5dda46d2 (MD5) / Dissertacao (Mestrado Profissionalizante em Lasers em Odontologia) / IPEN/D-MPLO / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP; Faculdade de Odontologia, Universidade de Sao Paulo, Sao Paulo

A reconstrução do rebordo atrófico da maxila pode ser feita por diversos materiais e técnicas. A utilização do enxerto ósseo em bloco retirado da sinfise ou do ramo mandibular tem sido empregado devido a qualidade óssea, reduzida morbidade e fácil acesso, sendo indicado na reconstrução dos defeitos localizados dos maxilares atróficos. O objetivo deste estudo foi determinar e comparar o índice de sobrevivência de implantes dentários instalados no remanescente osseo da maxila ou em áreas da maxila parcialmente reconstruídas utilizando-se enxerto ósseo em bloco retirado da sinfise ou ramo mandibular. Foram avaliados os prontuários de 731 pacientes atendidos entre agosto de 1999 a marco de 2009, sendo a amostra constituída por 255 pacientes. Dessa amostra, foram instalados 461 implantes dentários no tecido ósseo remanescente da maxila, 100 implantes dentários em áreas da maxila parcialmente reconstruídas com enxerto em bloco da sinfise (39 sitios) e 52 implantesdentarios em áreas da maxila parcialmente reconstruídas com enxerto em bloco do ramo mandibular (33 sitios). O índice de sobrevivência dos implantes dentários foram, respectivamente, 95%, 94% e 96% não havendo diferença estatisticamente significante (p>0,05) entre os grupos avaliados. Os procedimentos reconstrutívos da maxila, por meio do enxerto ósseo em bloco retirado da sinfise ou do ramo mandibular, não se constituem fator isolado relacionado a falha do tratamento com implantes dentários. / The reconstruction of atrophic maxillary ridge can be made with the use of different materials and techniques. The use of block bone grafts harvesting of the symphysis or mandibular ramus has been employed due to bone quality, low morbidity and access easy, being indicated in the reconstruction of atrophic jaws defects located. The aim of this study was to determine and compare the survival rate of dental implants inserted in the maxilla residual alveolar ridge or local alveolar defects in the maxilla reconstructed with block bone grafts of the symphysis or mandibular ramus. This study evaluated 731 patients files, who was treated between August 1999 and March 2009. The sample consisted in 255 patients, where 461 dental implants were installed in the maxilla residual alveolar ridge, 100 dental implants in local defects of the maxilla reconstructed with symphysis block bone graft (39 sites), and 52 dental implants in local defects of the maxilla reconstructed with block bone graft from the mandibular ramus (33 sites). The success rate of dental implants installed were, respectively, 95%, 94% e 96%, with no statistically significant difference (p>0.05). The reconstructive procedures of the maxilla, with block bone grafts harvesting of the symphysis or mandibular ramus, are not an independent risk factor for implant failure treatment.

Made available in DSpace on 2014-10-09T12:54:55Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:07:32Z (GMT). No. of bitstreams: 1 12799.pdf: 2207492 bytes, checksum: b4b02c1b606e22ff23dfa5bb5dda46d2 (MD5) / Dissertacao (Mestrado Profissionalizante em Lasers em Odontologia) / IPEN/D-MPLO / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP; Faculdade de Odontologia, Universidade de Sao Paulo, Sao Paulo

Abstract Reduction of morbidity in osseous reconstruction of cranio-maxillofacial bony defects could come from development of less invasive bone graft harvesting techniques or by elimination of bone graft donor sites using a bone graft substitute. This work studies outcomes and morbidity associated with these two approaches. A power-driven trephine was used to harvest bone from the anterior iliac crest using a minimally invasive surgical technique. Initially the safety of the technique was evaluated in a cadaver model. Twenty-five freshly preserved adult cadavers had a total of 250 cancellous cores of bone harvested from 50 anterior iliac crest sites. Twenty intentional perforations were made to the maximum depth possible with the instrumentation tested. No encroachment upon the peritoneum was found. A total of 84 patients had 333 cores of cancellous bone harvested using the same approach with a complication rate of 3.6% and a patient satisfaction rate of 98.8%. In a further 76 patients the motorized trephine method was compared to traditional open iliac crest corticocancellous block harvesting. The trephine group ambulated earlier, required fewer days of hospital stay and had significantly lower pain scores than the open iliac crest group. Coral-derived granules were used as a xenograft bone graft substitute to treat bony defects in the cranio-maxillofacial skeletons of 36 patients with 54 sites and followed for 12 to 36 months. The augmentations produced satisfactory results with the following complications noted: overt wound infection 1.8%, wound irritation 3.8% and clinically evident resorption in 9.3% of augmented sites. Coral-derived granules were then used to treat 48 dento-alveolar defects in 21 growing patients with trauma induced tooth-loss in the anterior maxilla and elective ankylosed tooth removal in the posterior maxilla and mandible. Coral granules were significantly more efficacious in reconstructing alveolar defects in the posterior maxilla or mandible (93.5%), than the anterior maxilla (17.6%). The minimally invasive technique using a power driven trephine was successful at reducing morbidity from bone graft harvesting at the anterior iliac crest. Coral-derived granules can be used in selected situations as a bone graft substitute and minimize post surgical morbidity by eliminating the bone graft donor site.

Hundreds of thousands of vascular bypass grafts are implanted in the United States every year, but there has yet to be an ideal graft material to substitute for one’s own autologous vessel. Many synthetic materials have been shown to be successful vessel replacements; however, none have been proven to exhibit the same mechanical properties as native vessels, one of the most important criteria in selecting a vascular graft material. Part of this issue is due to the fact that, currently, there is no “gold standard” for testing the longitudinal and transverse tensile properties of small diameter tubular materials. While there are ASTM and ISO standards that suggest ways to test tubes in their original form, many researchers have published tensile strength data based on cutting the tube and testing it as a flat sample. Thus, it was the aim of this thesis to understand, establish, and implement accurate tensile testing methods of small diameter polymers in their original, tubular state on Cal Poly’s campus. Two test fixtures were created based on specified design criteria in order to test materials in their tubular form in both the longitudinal and transverse directions. Both fixtures were successful in testing PLGA and ePTFE samples, and statistical data was gathered for the transverse test fixture. The new transverse test fixture was tested against the current method of testing, and a significant (α = 0.05) difference between methods was established for ultimate tensile strength. This analysis, however, cannot determine which test method is more accurate, thus more extensive testing is required to verify the design of both fixtures. By developing a method for testing small diameter polymers in tubular form on Cal Poly’s campus, it allows for more testing of various small diameter tubes and more comparative data to validate each design. It also demonstrates a need for a more detailed and widespread standardization of testing for small diameter tubes, especially in vascular substitute applications where the ideal vessel replacement has yet to be found.

<p> Polymers and block copolymers have been grafted from hard and soft polymer micro-spheres by atom transfer radical polymerization (ATRP) and ring opening polymerization (ROP). The hard and soft micro-spheres were prepared by precipitation polymerization of divinylbenzene-80 (DVB80), and of DVB80/hydroxyethylmethacrylate (HEMA), respectively, in neat acetonitrile.</p> <p> Residual vinyl groups in the hard, poly(DVB80) micro-spheres were hydrochlorinated to form benzyl chloride groups that subsequently served as ATRP initiators for poly(styrene) and poly(styrene-block-4-methylstyrene) grafts. Hydrophilic poly(HEMA) and poly(2-( dimethylamino)ethyl methacrylate) poly(DMAEMA) were also grafted from hard micro-spheres containing bromopropionates, using ATRP in the presence of CuBr/Me4Cyclam.</p> <p> Hydroxy groups in soft, poly(DVB80-co-HEMA) micro-spheres were used directly as initiators for ring opening polymerization of ε-caprolactone catalyzed by aluminum compounds. In the addition, they were reacted with α-bromopropionyl bromide to form ATRP initiators.</p> <p> Several combinations of ATRP-ATRP and ROP-ATRP with different monomers were carried out using these initiator micro-spheres. In particular, the soft micro-spheres grafted with poly(methacrylic acid), poly(methylmethacrylate), poly(methylmethacrylate-block-dimethylaminoethylmethacrylate), poly(methylmethacrylate-block-trimethylammoniumethylmethacrylate), poly(methylmethacrylate-block-HEMA), poly(methylmethacrylate-block-glycidylmethacrylate), poly(ε-caprolactone-block- methylmethacrylate), poly(ε-caprolactone-block-dimethylaminoethylmethacrylate).</p> <p> The internal morphology of these homo and block copolymer grafted microspheres was studied using electron microscopy and x-ray microspectroscopy.</p> / Thesis / Doctor of Philosophy (PhD)

Regenerative medicine involves formation of tissue or organ for replacement of a wounded or dysfunctional tissue. Healthy cells extracted from the patient are expanded and are seeded on a three-dimensional biodegradable scaffold. The structure is then placed in a bioreactor and is provided with nutrients for the cells, which proliferate and migrate throughout the scaffold to eventually form a desired to tissue that can be transplanted into the patient's body.  Inability to monitor this complex process of regeneration in real-time makes control and optimization of this process extremely difficult. Histology, the gold standard used for tissue structural assessment, is a static technique that only provides "snapshots" of the progress and requires the specimen to be sacrificed. This inefficiency severely limits our understanding of the biological processes associated with tissue growth during the in vitro pre-conditioning phase. Optical Coherence Tomography (OCT) enables imaging of cross sectional structure in biological tissues by measuring the echo time delay of backreflected light. OCT has recently emerged as an important method to assess the structures of physiological, pathological as well as tissue engineered blood vessels. The goal of the present study is to develop an imaging system for non-destructive monitoring of blood vessels maturing within a bioreactor. Non-destructive structural imaging of tissue-engineered blood vessels cultured in a novel bioreactor was performed using free-space and catheter-based OCT imaging, while monitoring of the endothelium development was performed using a fluorescence imaging system that utilizes a commercial OCT catheter. The project included execution of three specific aims. Firstly, we developed OCT instrumentation to determine geometrical and optical properties of porcine and human skin in real-time. The purpose of the second aim was to assess structural development of tissue-engineered blood vessels maturing in a bioreactor. We constructed a novel quartz-based bioreactor that will permit free space and catheter-based OCT imaging of vascular grafts. The grafts were made of biodegradable PCL-collagen and seeded with multipotent mesenchymal cells. We imaged the maturing grafts over 30 days to assess changes in graft wall thickness. We also monitored change in optical properties of the grafts based on free-space OCT scanning.   Finally, in order to visualize the proliferation of endothelial cells and development of the endothelium, we developed an imaging system that utilizes a commercial OCT catheter for single-cell-level imaging of the growing endothelium of a tissue-engineered blood vessel. We have developed two modules of an imaging system for non-destructive monitoring of maturing bioengineered vascular grafts. The first module provides the ability to non-destructively examine the structure of the grafts while the second module can track the progress of endothelialization. As both modules use the same endoscope for imaging, when operated in sequence, they will produce high-resolution, three-dimensional, structural details of the graft and two-dimensional spatial distribution of ECs on the lumen. This non-destructive, multi-modality imaging can be potentially used to monitor and assess the development of luminal bioengineered constructs such as colon or trachea. / Ph. D.

Thesis (PhD)--Stellenbosch University, 2001. / ENGLISH ABSTRACT: Please refer to fulltext for abstract. / AFRIKAANSE OPSOMMING: Sien volteks vir opsomming.

Suportes eletrofiados para crescimento celular são de interesse para a engenharia de tecidos, principalmente em função de sua estrutura em forma de rede tridimensional de fibras de diâmetro nanométrico. Esta arquitetura especial permite a geração de elevada área superficial e porosidade, características importantes para a adesão, proliferação e infiltração de células para o interior do suporte. A utilização de um suporte eletrofiado como enxerto vascular necessita ainda que este apresente excelentes propriedades mecânicas, associadas a uma elevada biocompatibilidade. Neste trabalho mostramos que estas propriedades podem ser alcançadas a partir da eletrofiação de uma co-solução de PET e colágeno gerando um material híbrido, visto que PET apresenta excelentes propriedades mecânicas e o colágeno é o principal componente da matriz extracelular. A obtenção dos suportes eletrofiados de PETcolágeno mostrou ser possível utilizando-se como solvente HFIP e HFIP/TFA 7:2. No entanto, neste último, o colágeno é completamente degradado durante o processo de solubilização. Fixando-se os parâmetros de eletrofiação, a morfologia da malha obtida mostrou ser dependente da relação massa PET/massa colágeno, concentração total da solução e solvente utilizado. Foram obtidos materiais com distribuição de diâmetros unimodal e bimodal, além de materiais com formato em fitas e teias entre as fibras. Ainda, PET e colágeno formam malhas de composição complexa, nas quais são encontradas fibras compostas de materiais puros, mas também formam blendas em que os dois materiais encontram-se misturados em uma mesma fibra. Os materiais S8,2 S4,6 foram caracterizados química-, mecânica- e biologicamente. Observou-se que, para filmes planos, estes materiais apresentaram energia de superfície mais próxima da do colágeno, o que justifica a melhor adesão celular em S8,2 e S4,6 do que no PET. S8,2 mostrou ter valores de módulo de elasticidade e elongação máxima próximos ao da artéria femoral, enquanto que S4,6 apresentou-se como um material quebradiço. Os ensaios de crescimento celular utilizando fibroblastos, um modelo de tecido conjuntivo (linhagem 3T3-L1) e células endoteliais, um modelo de tecido arterial e venoso (HUVECs) comprovaram a excelente adesão e proliferação celular nos suportes celulares. S8,2 apresentou-se como o melhor material frente às células HUVECS, enquanto que S4,6 foi o melhor material frente às células 3T3-L1. Propõe-se a utilização de S8,2 como um biomaterial para enxertia vascular e S4,6 como material de recobrimento de próteses já utilizadas. / Scaffolds obtained by electrospinning for cellular growth are of interest for materials engineering, especially considering its structure in the form of a three-dimensional fiber mesh of nanometric diameter. This special architecture allows the generation of larger surface areas and higher porosity structures, and also important characteristics for the adhesion, proliferation and infiltration of cells into the scaffold. The use of an electrospun scaffold as a vascular graft additionally requires excellent mechanical properties, associated with a high biocompatibility level. In this study we demonstrate that these properties can be achieved by means of electrospinning of PET and collagen co-solution producing a hybrid material, considering that PET possesses excellent mechanical properties and that collagen is the principal component of the extracellular matrix. The production of electrospun scaffolds of PET/collagen is shown to be possible using HFIP and HFIP/TFA 7:2 as solvents. However, in this last one, the collagen is completely degraded during the solubilization process. If the electrospinning parameters are maintained constant, the morphology of the mesh obtained was found to be dependent on the ratio of PET/collagen (w/w), total concentration of the solution and solvent employed. Materials were obtained with unimodal and bimodal diameter distribution, as well as material in the form of ribbons and mesh between the fibers. In addition, PET and collagen form a mesh of complex composition, in which fibers composed by pure and blended materials were found. The materials PET/collagen 80:20 (S8,2) and PET/collagen 40:60 (S4,6) were characterized chemically, mechanically and biologically. It was observed that, for spincoated films, these materials present a surface energy closer to that of collagen, explaining the better cellular adhesion in S8,2 e S4,6 than for PET. S8,2 presents very similar elasticity and elongation modulus values to the femoral artery, while S4,6 is a brittle material. The cellular growth experiments using fibroblasts as a model of conjunctive tissue (3T3-L1) and endothelial cells as a model of arterial and venous tissue (HUVEC) proved the excellent adhesion and cellular proliferation on the cellular PET/collagen scaffolds. S8,2 was shown to be the best material considering HUVEC cells, while S4,6 was the best material considering 3T3-L1 cells. According to the results obtained, the use of S8,2 is proposed as a biomaterial for vascular grafts and S4,6 as a material for a coating for vascular grafts prostheses.

Traumas nas asas de aves são muito comuns, causando lesões em tecidos moles e ossos, e tendem, muitas vezes a causar desvascularização da região, o que implica em complicação no tratamento além de facilitar a instalação de processo infeccioso. Com o objetivo de estudar possível vascularização via enxerto muscular pediculado, foram utilizados 12 pombos, divididos em dois grupos iguais (E e S), para a avaliação do uso de enxerto pediculado de músculo peitoral como técnica de revascularização de defeito criado em porção distal de bíceps braquial. As asas contralaterais de todos os animais foram utilizadas para a avaliação termográfica, sendo este grupo de n=12 denominado C. As asas contralaterais de dois animais foram utilizadas como controle anatômico para a avaliação histomorfométrica, grupo este denominado A. Realizaram-se avaliações clínica, termográfica, angiográfica e histomorfométrica para quantificação e qualificação da vascularização, e determinação da viabilidade desta técnica, em até vinte e um dias. A técnica causou pouca morbidade, exceto em dois animais do grupo E que apresentaram necrose parcial do enxerto, porém isto não resultou em falha da técnica. As avaliações termográficas demonstraram que imediatamente após a cirurgia, tanto leito doador, quanto leito receptor apresentaram redução da temperatura, porém esta temperatura aumentou gradativamente, sendo que no grupo E, a temperatura, aos sete dias foi mais baixa, quando compaprada ao grupo S e ao grupo A, e aos catorze dias não houve diferença significativa entre os grupos. A avaliação angiográfica post mortem determinou patência de vasos principais e secundários em todos os animais, comprovando tratar-se de técnica que causa baixa mortificação do tecido no sítio doador, e na asa. A avaliação histomorfométrica incluiu dados de área total de vasos por amostra, área total de tecido, diâmetro médio dos vasos, número absoluto de vasos, e percentagem de tecido ocupada por vasos. Tal avaliação demonstrou aumento importante da vascularização dos dois grupos avaliados, sendo que o único parâmetro que apresentou diferença entre os dois, foi o número de vasos, aumentado no grupo E. Conclui-se que o enxero apresenta neovascularização importante, e provavelmente cria ambiente adequado para promover cicatrização de lesão pobremente vacularizadas em aves. / Trauma in avian wings is very common, causing lesions in soft tissue and bones, and they tend to, many times, cause avascularization of the region, which aggravates treatment and allows for the installation of infectious processes. Twelve pigeons, divided in two equal groups (E and S) were used for the evaluation of the use of a pectoral muscle flap as revascularization technique for a distal biceps brachii defect. Contralateral wings os all animals were used for termographic evaluation, and this group with n=12 was called C. Contraletarl wings of two animals were used as anatomic control for the histomorphometric evaluation, and this group was called A. Clinical, termographic, angiographic and histomorphometric evaluations were made to quantify and qualify the vascularization, and determine the viability of this technique. The technique caused little morbidity, except for two animals in group E, who had partial necrosis of the grafts, but that didnt result in failure of the technique. Termography showed that after surgery, both, donor and receptor sites had a reduced temperature, but it increased gradually. Group E showed a lower temperature at seven days, when compared to group S and to group C, and at fourteen days, there was no significant difference between groups. Post mortem angiografic evaluation determined patency of main and secondary vessels in all animals, proving to be a low morbidity technique for the donor site and for the wing. Histomorphometric evaluation includes total area of vessels and of soft tissue, mean vessel diameter, total vessel number and percentage of soft tissue covered by vessels. This evaluation showed and important increase of vascularization of both groups, and only total number of vessels was different among groups, being bigger in group E. We conclude that the graft shows important neovascularization, and probably creates adequate environment for the healing of little vascular bird wounds.